From Medan there is a local bus (no air-con) about every hour for 22,000 rupiah (Oct 08) if you pay on the bus. The journey takes 4-6 hours, depending on the traffic condition.
From Medan TOBATRANSPORTER +6285261492668 or email add email@example.com ; its a private van (Nice and comfort Car) 5 seaters or 7 seaters from the airport of medan (Polonia) its take 500,000 IDR and for share taxi its take 100,000 IDR per person (5 seaters); alternatively many taxi trans around medan like Paradep Taxi, Raja Taxi and etc
Take a ferry boat to cross over to Samosir island.
Water Scooters (150,000Rp per half hour, with a guide on-board)
Speed boat rides
Self paddle "kiddle ride" boats (40,000Rp per hour)
b.caro coffe shop, haranggaol st 114 (5 minutes from down town parapat,2 minutes from tigaraja harbour), ☎ 062541306. get the best coffee in this town "when u come to parapat u must be try our coffee "3000per cup.
Charlie's Guesthouse - good place, meaning cheap and central. Overlooks the market (a bit noisy especially on Saturday) and is very close to the ferry station. Rooms are about 30,000 rupiah, pretty clean and with shower (2006).
Niagara Hotel and Resort - One of the better hotel you can get there, though only 2 to 3 stars. Can be crowded with families and Indonesians during peak period (weekends and public holidays) http://www.niagaralaketoba.com/